Mechanism for periodically forging screws

ABSTRACT

A periodically transferring mechanism for a self-drilling screw forming machine includes a gear system and a clutch device which controls the engagement of the contact between the contact member of the clutch device and the hosing mounted on the driven shaft. The clutch device is eccentrically connected to a idle gear which has two times of the number of teeth to the active gear so that the clutch device periodically contacts the hosing. A rating switch device is used to switch the transferring rate of the mechanism from 1:1 mold to 2:1 mold.

FIELD OF THE INVENTION

[0001] The present invention relates to a mechanism used in self-drilling screw forming machines and provides two strokes to form the screws. The mechanism effectively protects the pointing dies.

BACKGROUND OF THE INVENTION

[0002] Conventional self drilling screw forming machines known to applicant includes a feeding device for sending material to a clamping device which then rotated to send the material to the pointing dies which forge the material to be a drill-point. The toughness of the material decides the number of strokes needed, wherein a harder material such as stainless steel has to be treated two times to form a screw. The conventional mechanism for providing two strokes to form a screw employs a chain engaged between two chainwheels. A driving chain is overlapped onto the chain at a proper length so that the driving chain will periodically drive a chainwheel when the chain is moving so as to achieve the purpose of two-stroke machining. However, the two ends of the driving chain bear a huge tension and stress so that it will be lengthened or broken within a short period of time. Besides, the inherent shortcomings of using chains are existed and one of which is that the transmission of chains has less precision which could damage the parts and dies of the machine.

SUMMARY OF THE INVENTION

[0003] The primary object of the present invention is to provide a mechanism that provides a periodical movement between the dies and the clamping device so that the number of strokes is two.

[0004] The other object of the present invention is that the transmission of the mechanism is made by gear system so that it has a high transmission precision.

[0005] Another object of the present invention is that the mechanism has an adjusting device that is able to transfer the mechanism from two-stroke to one-stroke so as to meet different machining requirements according to the material.

[0006] The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a perspective view of a part of the self-drilling screw forming 15 machine of the present invention;

[0008]FIG. 2 is a perspective view to show the working end of the self-drilling screw forming machine of the present invention;

[0009]FIG. 3 is a perspective view to show the working end of the self-drilling screw forming machine of the present invention covered by a casing;

[0010]FIG. 4 is an exploded view to show the mechanism of the self-drilling screw forming machine of the present invention;

[0011]FIG. 5 is another exploded view to show the mechanism of the self-drilling screw forming machine of the present invention;

[0012]FIG. 6 shows a top view of the mechanism of the self-drilling screw forming machine of the present invention;

[0013]FIGS. 7A and 7B show a side view of the mechanism of the self-drilling screw forming machine of the present invention;

[0014]FIG. 8 is a side view to show the engagement of the gears when the number of stroke is changed, and

[0015]FIGS. 9 and 10 show the steps of forging actions and a chart showing the forging force and the strokes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring to FIGS. 1 and 2, the mechanism of the present invention is connected to a self-drilling screw forming machine “A” and comprises a feeding device 1, an active shaft 2, a periodical transmission mechanism 3, a clamping device 4 and a dies 5. The feeding device 1 has a feeding path 1-1 so as to send material to a disk 4-1 of the clamping device 4 and the material can be pressed by the dies 5. The action transferred by the active shaft 1 via the periodical transmission mechanism 3 is transformed into a proper rating movement so that the material clamped by the clamping device 4 can be pressed to screws according to the diameters of the screws.

[0017] Referring to FIGS. 3 to 7, the periodical transmission mechanism 3 includes a base 10, a gear system 20, a connection member 30, a clutch device 40, a casing 50 and a rating switch device 60. The active shaft 2 is connected to the base 10 so as to drive the periodical transmission mechanism 3, and the action is transferred to the driven shaft 6 of the clamping device 4 by a Geneva stop mechanism.

[0018] The gear system 20 includes an active gear 21, a first idle gear 22, a second idle gear 23 and a driven gear 24 on which a housing 25 and a top plate 26 are mounted. The top plate 26 has a position hole 261. The active gear 21 is fixedly mounted to the active shaft 2 and the first idle gear 22 is engaged with the active gear 21, the second idle gear 23 engaged between the second idle gear 22 and the driven gear 24 which is mounted to the driven shaft 6. A slot 241 is defined in a top surface of the driven gear 24 and a hole 242 is defined in an inside of one end of the periphery of the slot 241. The hosing 25 has a flange 251 extending outward from an outer periphery thereof and a groove 252 is defined longitudinally in the outer periphery of the hosing 25. The number of teeth of the first idle gear 22 is twice of the number of teeth of the active gear 21, the second idle gear 23 and the driven gear 24.

[0019] The connection member 30 is a pin 31 having an insertion 311 at a lower end thereof and a block 32 extends outward from a mediate portion of the pin 31. The block 32 has protrusion 321 on a center on the bottom thereof and an inclined surface 322 on each of two ends of the block 32. A spring 33 is mounted to the top of the pin 31 which is inserted in the grove 252, the spring 33 is then biased between the top plate 26 and the block 32 so that the insertion 311 is inserted in the hole 242 in the slot 241. The action coming from the driven gear 24 is transferred to the connection member 30, the hosing 25 and the driven shaft 6.

[0020] The clutch device 40 has a crank 41, a rod 42, a retractable bar 43, a contact member 44 and a fix member 45 which is fixed on the base 10. One end of the crank 41 is pivotably and eccentrically engaged with the first idle gear 22, the other end of the crank 41 is connected to the rod 42 which has a recess 421 for receiving a spring 46 therein. A pin 47 is fixedly inserted in a recess 431 in the retractable bar 43 so that the retractable bar 43 can be movable in the recess 421 of the connection rod 42. The contact member 44 is connected to the retractable bar 43 and has a contact surface 441 which contacts the flange 251 of the hosing 25. A concave surface 442 is defined on a top of the contact member 44 and two inclined surface 443 are defined on two ends of the contact member 44. The inclined surface 322 on the block 32 of the connection member 30 can move upward along the inclined surface 443 on the contact member 44 when the connection member 30 is rotated with the driven gear 24. The protrusion 321 on the block 32 may engage with the concave surface 442 on the contact member 44 when the driven gear 24 is rotated. The connection member 30 compresses the spring 33 when the block 32 is raised by the contact member 44, and the pin 31 is then removed from the slot 241 so that the driven gear 24 self rotates on the driven shaft 6. The hosing 25 is then still without any action because the contact member 44 contacts the block 32. The concave surface 442 on the contact member 44 has a stop recess 444 so as to stop the contact member 44. The connection rod 42 is inserted in a hole 451 in the fix member 45 so that the connection rod 42 can be moved in stable.

[0021] The casing 50 is fixed to the base 10 and a cover 51 is removably connected to the casing 50 for convenience of maintenance. A convex portion 52 is located on the casing 50 so as to receive the driven shaft 6, the hosing 25 and the top plate 26. A central opening and two holes 53 are defined in the convex portion 52. The two holes 53 are located in communication with the position hole 261 in the top plate 26 and the stop recess 444 in the contact member 44.

[0022] The rating switch device 60 is mounted on the convex portion 52 and has a receiving area 61 on a side of the rating switch device 60. The receiving area 61 is sealed by a cover 62 to which an active gear shaft 63, a first gear shaft 64 and a second gear shaft 65 are rotatably extended. A switch member 66 is connected to the casing of the rating switch device 60 and connected to the active gear shaft 63 so as to control the active gear shaft 63. Two passages 67 are defined through the casing of the rating switch device 60 so that a first rack 68 and a second rack 69 are inserted therein. The first rack 68 includes a toothed sleeve 681 connected to a hat member 683 having guide slot 682. A core 685 with a spring 684 mounted thereto extends through the hat member 683. A position pin 686 is connected to the core 685 and movable in the guide slot 682. The toothed sleeve 681 is engaged with the first gear shaft 64 so as to move up and down. A position pin 687 on a lower end of the core 685 prevents the rotation of the top plate 26, hosing 25 and the driven shaft 6 from rotation because of initial movement. The second rack 69 is engaged with the second gear shaft 65 and movable up and down. A stop pin 691 on the lower end of the second rack 69 is engaged with the stop recess 444 in the contact member 44 via the hole 53 to limit the engagement between the contact member 44 and the flange 251. By this way, the action of the driven gear 24 is transferred to the driven shaft 6 without interruption.

[0023] Referring to FIGS. 7A and 7B, the number of teeth of the active gear 21 and the driven gear 24 is the same so that when the active gear 21 rotates one revolution, the driven gear 24 rotates one revolution. The number of teeth of the first idle gear 22 is two times of the teeth of the active gear 21, the second idle gear 23 and the driven gear 24, and the clutch device 40 is eccentrically connected to the first idle gear 22. When the active gear 21 rotates two revolutions, the first idle gear 22 rotates only on revolution, so that the clutch device 40 rotates one revolution and the contact member 44 contacts the flange 251 once. In other words, when the contact member 44 contacts the flange 251, the connection member 30, the hosing 25 and the driven shaft 6 are disengaged from the slot 241 in the driven gear 24. Therefore, when the active gear 21 rotates two revolutions, the first idle gear 22 rotates once and the driven gear 21 is disengaged from the driven shaft 6 once. In order to prevent that the top plate 26, the hosing 25 and the driven shaft 6 from rotating because the initial force when the connection member 30 is disengaged from the driven gear 24, the protrusion 321 on the block 32 is engaged with the concave surface 442 to position the pin 31 and the hosing 25. Besides, when rotating the switch member 66, the first rack 68 is moved downward by the first gear shaft 64 and contacts the top plate 26 and when the block 32 of the connection member 30 contacts the contact member 44, the position pin 687 on a lower end of the core 685 is engaged with the position hole 261 in the top plate 26. By the two ways mentioned above, the top plate 26, the hosing 25 and the driven shaft 6 are periodically rotated.

[0024] As shown in FIG. 8, when rotating the switch member 60 counter-clockwise, the first gear shaft 64 rotates clockwise and drives the first rack 68. The second gear shaft 65 rotates clockwise and drive the second rack 69 upward so that the clutch device 40 can be functioned. When the switch member 60 is rotated clockwise, the first rack 68 goes upward away from the top plate 26 and the second rack 69 moves downward, and the stop pin 691 on the lower end of the second rack 69 is engaged with the stop recess 444 in the contact member 44 so as to avoid the contact member 44 from contacting the flange 251. By this way, the pin 31 is engaged with the slot 241 in the driven gear 24 and the periodical transmission mechanism 3 is operated in 1:1 mold. In other words, the molds of 1:1 or 2:1 can be switched by rotating the switch member 66.

[0025] As shown in FIGS. 9 to 11, the periodical transmission mechanism 3 makes the dies 5 press twice with the clamping device rotating only once so that the material is pressed twice to form a product. The chart showing the relationship between the force of strokes and the distance of the strokes shows that the dies 5 is applied a smaller force in the first stroke (stroke I) compared with the second stroke (stroke II) and the distance or depth of press is larger. By the two-stroke action, the quality of the final products are increased and is available to the manufacturing of large diameter screws, long screws and hard material.

[0026] While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention. 

What is claimed is:
 1. A periodically transferring mechanism comprising: a base (10) having an active shaft (2) and a driven shaft (6) connected thereto; a gear system (20) including an active gear (21), a first idle gear (22), a second idle gear (23) and a driven gear (24) on which a housing (25) and a top plate (26) are mounted, a number of teeth of the first idle gear (22) being twice of the number of teeth of the active gear (21), the second idle gear (23) and the driven gear (24), the active gear (21) fixedly mounted to the active shaft (2), the driven gear (24) mounted to the driven shaft (6), a slot (241) defined in a top surface of the driven gear (24) and a hole (242) defined in an inside of one end of the periphery of the slot (241), a hosing (25) mounted to the driven shaft and a flange (251) extending outward from a periphery of the hosing, a groove (252) defined longitudinally in an outer periphery of the hosing (2), a top plate (26) connected to the hosing and the driven shaft; a connection member (30) engaged with the groove in the hosing and a block (32) extending outward therefrom, a spring (33) mounted to the connection member (30) which is inserted in the grove (252), the spring (33) biased between the top plate (26) and the block (32); a clutch device (40) having a crank (41), a rod (42), a retractable bar (43), a contact member (44) and a fix member (45), one end of the crank (41) pivotably and eccentrically engaged with the first idle gear (22) and the other end of the crank (41) connected to the rod (42) which has a recess (421) for receiving a spring (46) therein, the retractable bar (43) movable in the recess (421) of the connection rod (42), a contact member (44) connected to the retractable bar (43) and disengagably contacting the flange (251) of the hosing (25), and a casing (50) fixed to the base (10) and mounted to the gear system (20), the connection (30) and the clutch device (40), a convex portion (52) located on the casing (50) so as to receive the driven shaft (6), the hosing (25) and the top plate (26).
 2. The mechanism as claimed in claim 1, wherein the top plate (26) has a position hole (261) for being engaged with the connection member (30).
 3. The mechanism as claimed in claim 1, wherein connection member (30) is a pin (31) having an insertion (311) at a lower end thereof and the block (32) has a protrusion (321) on a center of the bottom thereof and an inclined surface (322) is defined on each of two ends of the block (32), the insertion (311) inserted in the hole (242) in the slot (241).
 4. The mechanism as claimed in claim 1, wherein a pin (47) is fixedly inserted in a recess (431) in the retractable bar (43) so that the retractable bar (43) can be movable in the recess (421) in the connection rod (42).
 5. The mechanism as claimed in claim 1, wherein the connection rod (42) is inserted in a hole (451) in the fix member (45).
 6. The mechanism as claimed in claim 1, wherein the contact member (44) has a contact surface (441) which contacts the flange (251) of the hosing (25), a concave surface (442) defined on a top of the contact member (44) and two inclined surface (443) defined on two ends of the contact member (44), the inclined surface (322) on the block (32) of the connection member (30) moving upward along the inclined surface (443) on the contact member (44) when the connection member (30) is rotated with the driven gear (24), the protrusion (321) on the block (32) engaging with the concave surface (442) on the contact member (44) when the driven gear (24) is rotated.
 7. The mechanism as claimed in claim 6, wherein the contact member (44) has a stop recess (444) so as to stop the contact member (44).
 8. The mechanism as claimed in claim 1, wherein the casing (50) has central opening and two holes (53) defined in the convex portion (52), the two holes (53) located in communication with the position hole (261) in the top plate (26) and the stop recess (444) in the contact member (44).
 9. The mechanism as claimed in claim 1, wherein a rating switch device is connected on the casing (50) and a receiving area (61) is defined in a side of the rating switch device (60), the receiving area (61) sealed by a cover (62) to which an active gear shaft (63), a first gear shaft (64) and a second gear shaft (65) are rotatably extended, a switch member (66) connected to the casing of the rating switch device (60) and connected to the active gear shaft (63), two passages (67) defined through the casing of the rating switch device (60) so that a first rack (68) and a second rack (69) are inserted therein, the first rack (68) engaged with the first gear shaft (64) so as to move up and down, a position pin (687) on a lower end of the first rack (68) engaged with the position hole (261) in the top plate (26), The second rack (69) is engaged with the second gear shaft (65) and movable up and down, a stop pin (691) on the lower end of the second rack (69) and engaged with the stop recess (444) in the contact member (44).
 10. The mechanism as claimed in claim 1, wherein the first rack (68) includes a toothed sleeve (681) connected to a hat member (683) having guide slot (682), a core (685) having a spring (684) mounted thereto and extending through the hat member (683), a position pin (686) connected to the core (685) and movable in the guide slot (682). 